Mounting File Systems

You can mount file systems in several ways. File systems can be mounted automatically when the system is booted, on demand from the command line, or through the automounter. The automounter provides many advantages to mounting at boot time or mounting from the command line. However, many situations require a combination of all three methods. Additionally, several ways of enabling or disabling processes exist, depending on the options you use when mounting the file system. See the following table for a complete list of the tasks that are associated with file system mounting.

Table 5-2 Task Map for Mounting File Systems

How to Mount a File System at Boot Time

If you want to mount file systems at boot time instead of using autofs maps, follow this procedure. This procedure must be completed on every client that should have access to remote file systems.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Add an entry for the file system to /etc/vfstab.

   Entries in the /etc/vfstab file have the following syntax:

   special  fsckdev  mountp  fstype  fsckpass  mount-at-boot  mntopts

   See the vfstab(4) man page for more information.

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   Caution - NFS servers that also have NFS client vfstab entries must always specify the bg option to avoid a system hang during reboot. For more information, see mount Options for NFS File Systems.

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Example 5-1 Entry in the Client's vfstab File

You want a client machine to mount the /var/mail directory from the server wasp. You want the file system to be mounted as /var/mail on the client and you want the client to have read-write access. Add the following entry to the client's vfstab file.

wasp:/var/mail - /var/mail nfs - yes rw

How to Mount a File System From the Command Line

Mounting a file system from the command line is often performed to test a new mount point. This type of mount allows for temporary access to a file system that is not available through the automounter.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Mount the file system.

   Type the following command:

   # mount -F nfs -o ro bee:/export/share/local /mnt

   In this instance, the /export/share/local file system from the server bee is mounted on read-only /mnt on the local system. Mounting from the command line allows for temporary viewing of the file system. You can unmount the file system with umount or by rebooting the local host.

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   Caution - All versions of the mount command do not warn about invalid options. The command silently ignores any options that cannot be interpreted. To prevent unexpected behavior, ensure that you verify all of the options that were used.

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Example 5-2 Using Mirror Mounts After Mounting a File System

This release includes the mirror mount facility. This new mounting technology can be used from any NFSv4 client accessing a second file system from an NFSv4 server. Once the first file system is mounted from the server using either the mount command or the automounter, then any file systems that are added to that mount point may be accessed. All you have to do is try to access the file system. The mirror mount occurs automatically. For more information, see How Mirror Mounts Work.

Mounting With the Automounter

Task Overview for Autofs Administration includes the specific instructions for establishing and supporting mounts with the automounter. Without any changes to the generic system, clients should be able to access remote file systems through the /net mount point. To mount the /export/share/local file system from the previous example, type the following:

% cd /net/bee/export/share/local

Because the automounter allows all users to mount file systems, root access is not required. The automounter also provides for automatic unmounting of file systems, so you do not need to unmount file systems after you are finished.

See Using Mirrormounts After Mounting a File System for information about how to mount additional file systems on a client.

How to Mount All File Systems from a Server

This release includes the mirror mount facility, which allows a client to access all available file systems shared using NFS from a server, once one mount from that server has succeeded. For more information, see How Mirror Mounts Work.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Mount the root of the exported namespace of the server.

   This command mirrors the file system hierarchy from the server on the client. In this case, a /mnt/export/share/local directory structure is created.

   # mount bee:/ /mnt

3. Access a file system.

   This command or any other command which accesses the file system causes the file system to be mounted.

   # cd /mnt/export/share/local

How to Disable Large Files on an NFS Server

For servers that are supporting clients that cannot handle a file over 2 GBytes, you might need to disable the ability to create large files.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Check that no large files exist on the file system.

   For example:

   # cd /export/home1
   # find . -xdev -size +2000000 -exec ls -l {} \;

   If large files are on the file system, you must remove or move these files to another file system.

3. Unmount the file system.

   # umount /export/home1

4. Reset the file system state if the file system has been mounted by using largefiles.

   fsck resets the file system state if no large files exist on the file system:

   # fsck /export/home1

5. Mount the file system by using nolargefiles.

   # mount -F ufs -o nolargefiles /export/home1

   You can mount from the command line, but to make the option more permanent, add an entry that resembles the following into /etc/vfstab:

   /dev/dsk/c0t3d0s1 /dev/rdsk/c0t3d0s1 /export/home1  ufs  2  yes  nolargefiles

How to Use Client-Side Failover

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. On the NFS client, mount the file system by using the ro option.

   You can mount from the command line, through the automounter, or by adding an entry to /etc/vfstab that resembles the following:

   bee,wasp:/export/share/local  -  /usr/local  nfs  -  no  ro

   This syntax has been allowed by the automounter. However, the failover was not available while file systems were mounted, only when a server was being selected.

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   Note - Servers that are running different versions of the NFS protocol cannot be mixed by using a command line or in a vfstab entry. Mixing servers that support NFS version 2, version 3, or version 4 protocols can only be performed with autofs. In autofs, the best subset of version 2, version 3, or version 4 servers is used.

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How to Disable Mount Access for One Client

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Disable mount access for one client.

   # share -F nfs  ro=-rose:eng /export/share/man

   or=-rose:eng

   The access-list that allows read-only mount access to all clients in the eng netgroup except for the host named rose

   /export/share/man

   The file system to be shared.

How to Mount an NFS File System Through a Firewall

To access file systems through a firewall, use the following procedure.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Manually mount the file system by using a command such as the following:

   # mount -F nfs bee:/export/share/local /mnt

   In this example, the file system /export/share/local is mounted on the local client by using the public file handle. An NFS URL can be used instead of the standard path name. If the public file handle is not supported by the server bee, the mount operation fails.

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   Note - This procedure requires that the file system on the NFS server be shared by using the public option. Additionally, any firewalls between the client and the server must allow TCP connections on port 2049. All file systems that are shared allow for public file handle access, so the public option is applied by default.

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How to Mount an NFS File System Using an NFS URL

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. (Optional) If you are using NFS version 2 or version 3, manually mount the file system by using a command such as the following:

   # mount -F nfs nfs://bee:3000/export/share/local /mnt

   In this example, the /export/share/local file system is being mounted from the server bee by using NFS port number 3000. The port number is not required and by default the standard NFS port number of 2049 is used. You can choose to include the public option with an NFS URL. Without the public option, the MOUNT protocol is used if the public file handle is not supported by the server. The public option forces the use of the public file handle, and the mount fails if the public file handle is not supported.

3. (Optional) If you are using NFS version 4, manually mount the file system by using a command such as the following:

   # mount -F nfs -o vers=4 nfs://bee:3000/export/share/local /mnt

Setting up a DNS Record for a Federated File System Server

Once an appropriate DNS record is created, mounting a Federated File System is completed by the automounter once the mount point has been accessed. The DNS record for the server should look something like:

% nslookup -q=srv _nfs4._domainroot._tcp.example.com bee.example.com
Server:         bee.example.com
Address:        192.168.1.1

_nfs4._domainroot._tcp.example.com        service = 1 0 2049 bee.example.com.